• Journal of the Semiconductor & Display Technology
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• v.21 no.3
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• pp.74-79
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• 2022

In this study, the plasma corrosion resistance and the change in the number of contamination particles generated using the plasma etching process and cleaning process of coating parts for semiconductor plasma etching equipment were investigated. As the coating method, atmospheric plasma spray (APS) was used, and the powder materials were Y₂O₃ and Y₃Al₅O₁₂ (YAG). There was a clear difference in the densities of the coatings due to the difference in solubility due to the melting point of the powdered material. As a plasma environment, a mixed gas of CF₄, O₂, and Ar was used, and the etching process was performed at 200 W for 60 min. After the plasma etching process, a fluorinated film was formed on the surface, and it was confirmed that the plasma resistance was lowered and contaminant particles were generated. We performed a surface cleaning process using piranha solution(H₂SO₄(3):H₂O₂(1)) to remove the defect-causing surface fluorinated film. APS-Y₂O₃ and APS-YAG coatings commonly increased the number of defects (pores, cracks) on the coating surface by plasma etching and cleaning processes. As a result, it was confirmed that the generation of contamination particles increased and the breakdown voltage decreased. In particular, in the case of APS-YAG under the same cleaning process conditions, some of the fluorinated film remained and surface defects increased, which accelerated the increase in the number of contamination particles after cleaning. These results suggest that contaminating particles and the breakdown voltage that causes defects in semiconductor devices can be controlled through the optimization of the APS coating process and cleaning process.

• The Journal of Advanced Prosthodontics
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• v.9 no.2
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• pp.110-117
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• 2017

PURPOSE. This laboratory study assessed the effect of different dentin cleaning procedures on shear bond strength of resin cements for recementing prosthesis. MATERIALS AND METHODS. A $4{\times}4$ flat surface was prepared on the labial surface of 52 maxillary central incisors. Metal frames ($4{\times}4{\times}1.5mm$) were cast with nickel-chromium alloy. All specimens were randomly divided into 2 groups to be cemented with either Panavia F2.0 (P) or RelyX Ultimate (U) cement. The initial shear bond strength was recorded by Universal Testing Machine at a crosshead speed of 0.5 mm/min. Debonded specimens were randomly allocated into 2 subgroups (n = 13) according to the dentin cleaning procedures for recementation. The residual cement on bonded dentin surfaces was eliminated with either pumice slurry (p) or tungsten carbide bur (c). The restorations were rebonded with the same cement and were subjected to shear test. Data failed the normality test (P < .05), thus were analyzed with Mann Whitney U-test, Wilcoxon signed rank test, and two-way ANOVA after logarithmic transformation (${\alpha}=.05$). RESULTS. The initial shear bond strength of group P was significantly higher than group U (P = .001). Pc and Uc groups presented higher bond strength after recementation compared to the initial bond strength. However, it was significant only in Pc group (P = .034). CONCLUSION. The specimens recemented with Panavia F2.0 provided higher bond strength than RelyX Ultimate cement. Moreover, a tungsten carbide bur was a more efficient method in removing the residual resin cement and increased the bond strength of Panavia F2.0 cement after recementation.

• International Journal of Highway Engineering
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• v.9 no.3
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• pp.75-82
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• 2007

Washed wastewater generated from the intermittent cleaning process of the three tunnel sites located in the Seoul area showed high concentrations of SS, $COD_{Cr}$, T-N, $NH_3-N$, $NO_3-N$, Zn, Cu, Cr(+6), Mn, Mg, Phenol, $CN^-$ and E-Coli based on the water quality analysis. These characteristics of the deteriorative wastewater depend on the sampling method, cleaning frequency, released amount of washing water, inner material of tunnel wall, traffic volume, and type of drainage systems. Gravitational separation experiment of SS with collected tunnel wastewater showed considerable removal of pollutants such as 80% of $COD_{Cr}$, 30% of T-N and 90% of T-P simultaneously. GAC isotherm test was conducted to remove dissolved portion of the pollutants, and resulted in high removal efficiencies above 80% of $COD_{Cr}$, T-N, Zn, Cu, Mn, Phenol, CN in the experimental condition of GAC dosage of $50g/1/{\ell}$.

• Journal of Environmental Health Sciences
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• v.43 no.4
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• pp.298-306
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• 2017

Objectives: Since 1998, the Korea National Health and Nutrition Examination Survey (KNHANES) has been conducted in order to investigate the health and nutritional status of Koreans. The food intake data of individuals in the KNHANES has also been utilized as source dataset for risk assessment of chemicals via food. To improve the reliability of intake estimation and prevent missing data for less-responded foods, the structure of integrated long-standing datasets is significant. However, it is difficult to merge multi-year survey datasets due to ineffective cleaning processes for handling extensive numbers of codes for each food item along with changes in dietary habits over time. Therefore, this study aims at 1) cleaning the process of abnormal data 2) generation of integrated long-standing raw data, and 3) contributing to the production of consistent dietary exposure factors. Methods: Codebooks, the guideline book, and raw intake data from KNHANES V and VI were used for analysis. The violation of the primary key constraint and the $1^{st}-3rd$ normal form in relational database theory were tested for the codebook and the structure of the raw data, respectively. Afterwards, the cleaning process was executed for the raw data by using these integrated codes. Results: Duplication of key records and abnormality in table structures were observed. However, after adjusting according to the suggested method above, the codes were corrected and integrated codes were newly created. Finally, we were able to clean the raw data provided by respondents to the KNHANES survey. Conclusion: The results of this study will contribute to the integration of the multi-year datasets and help improve the data production system by clarifying, testing, and verifying the primary key, integrity of the code, and primitive data structure according to the database normalization theory in the national health data.

• Journal of Conservation Science
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• v.22
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• pp.99-108
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• 2008

This research aimed to provide a scientific methodology for removing white and black/brown coloured stains on the wall paintings of tombs of Jinpari No 1 and No 4. in the Democratic People's Republic of Korea. For the analysis of chemical composition of stains of the samples from the wall paintings, a microscope and SEM/EDX were used. The analysis confirmed that the fomula of white coloured stains should be $CaSO_4$ or $CaCO_3$ and the black/brown coloured stains should be $CaSO_4$ or $CaCO_3$ with soil deposition. Because of the difficulties of testing several cleaning solutions on sample patches of large area of the painting, the author considered a risk-free cleaning solution as being the most appropriate one, with Ammonium bicarbonate and Anion exchange resin showing satisfactory cleaning effect without visible side effects. For the removal of dense layer of stains, the research suggested that physical cleaning should be followed by applying a cleaning solution.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.3
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• pp.163-170
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• 2016

Regulations for the exhaust gas of diesel vehicles are being strengthened every year. Recently, diesel emission regulations for HC, CO, NOx, and particulate matter (PM) have been subject to very strict standards. In the future, the regulation of PM is expected to become stricter. Accordingly, diesel particulate filters (DPFs) have been applied to most diesel vehicles for PM reduction. With increasing engine mileage, ash and soot from the engine exhaust gas accumulate inside the DPF. This accumulation can damage the DPF or degrade engine performance. Therefore, efficient cleaning of the DPF is critical for the maintenance of the engine. If the DPF is well managed through regular cleaning, it can improve the power and fuel economy of the engine and reduce maintenance costs. Therefore, this study was performed to develop a high-efficiency cleaning method for DPFs and an apparatus that can more effectively clean out the accumulated ash and soot.

• The Korean Fashion and Textile Research Journal
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• v.13 no.6
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• pp.983-989
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• 2011

This study aimed to identify mordant effects of Chestnut hulls. The color of post and pre-mordanted fabrics were measured in terms of H, V, C, $L^*$, $a^*$, $b^*$, and K/S values. In addition, color fastness and antimicrobial activity were evaluated. The pre-mordant concentration of Chestnut hulls for cotton, mercerized cotton and silk was optimized to 50% (o.w.f.) and 70% (o.w.f.), respectively. Post-mordant concentration of Chestnut hulls of mercerized cotton, silk and cotton was optimized to 50% (o.w.f.) and 90% (o.w.f.), respectively. The hue of fabrics was influenced by mordant methods, such as pre-mordant and post-mordant, slightly. Wet cleaning fastness of pre-mordanted cotton and mercerized cotton fabrics was higher than that of post-mordanted fabrics. The wet cleaning fastness of silk fabrics was not affected by the mordant method, and their fastness were proved to be excellent. The dry cleaning fastness of post-mordanted cotton fabrics was higher than that of pre-mordanted cotton fabrics. The dry cleaning fastness of mercerized cotton and silk was proved to be excellent regardless of mordant methods. The antimicrobial activity of Oenothera odorata jacquin dyed fabrics and Chestnut hulls mordanted fabrics was proved to 99.9%, and their excellent antimicrobial activity remained after wet and dry cleaning.

• Journal of the Ergonomics Society of Korea
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• v.30 no.3
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• pp.427-435
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• 2011

Objective: The objective of this study was to evaluate a work of building cleaners using the ergonomic methods. Background: Previous studies about cleaning worker describe typical physical demands of this work. They found that the most significant risk factors associated with the physical work of cleaners are static loads and repetitive movements and high output of force. Method: A head of ergonomics estimation was work analysis(define of combined task, work tool, work time and frequency of combined task) and posture analysis of worker. Results: The results showed that combined task of building cleaners was classification sweeping, mopping(wet), mopping(oil), moving barrels/carts, dumping trash bags, scrubbing, arrangement of cleaning tool, arrangement of circumferential, moving of cleaning tool, and waiting. The work time of combined task such as mopping(wet) and scrubbing indicated high ratio. The posture analysis of building cleaners indicated high value in bending of the head, lower arm, and hands. Conclusion: The findings appear to indicate that building cleaner were related to high risk of work-related musculoskeletal disorders. So, building cleaner would be required an interventional strategy, improvement of cleaning tools and working environment. Application: If ergonomics rule can be integrated into existing cleaning tools and work environments, the risk of occupational injuries will be reduced.

• Particle and aerosol research
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• v.18 no.4
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• pp.129-136
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• 2022

The line width of circuits in semiconductor devices continues to decrease down to a few nanometers. Since nanoparticles attached to the patterned wafer surface may cause malfunction of the devices, it is crucial to remove the contaminant nanoparticles. Physical cleaning that utilizes momentum of liquid for detaching solid nanoparticles has recently been tested in place of the conventional chemical method. Dropwise impaction has been employed to increase the removal efficiency with expectation of more efficient momentum exchange. To date, most of relevant studies have been focused on drop spreading behavior on a horizontal surface in terms of maximum spreading diameters and average spreading velocity of drop. More important is the local liquid velocity at the position of nanoparticle, very near the surface, rather than the vertical average value. In addition, there are very scarce existing studies dealing with microdroplet impaction that may be desirable for minimizing pattern demage of the wafer. In this study, we investigated the local velocity distribution in spreading liquid film under various impaction conditions through the CFD simulation. Combining the numerical results with the particle removal model, we estimated an effective cleaning diameter (ECD), which is a measure of the particle removal capacity of a single drop, and presented the predicted ECD data as a function of droplet's velocity and diameter particularly when the droplets are microns in diameter.

• Journal of the Korean Society of Marine Environment & Safety
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• v.30 no.2
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• pp.233-238
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• 2024

The pipe cleaning process is a crucial step in the shipbuilding process of a shipyard. It involves removing foreign substances from the inside of the pipes before moving on to the stage of testing equipment after installing the pipes. If there are foreign substances inside the pipes and the equipment is tested, the foreign substances can enter the high-priced equipment and become a factor in the breakdown of pumps, gears, bearings, and other components. Especially in the case of pumps or hydraulic valves, even small foreign substances can lead to major accidents if they enter the equipment, and such equipment accidents can be a potential cause of major disasters, leading to accidents involving workers operating the equipment in the vicinity. Therefore, it is a process that shipyard customers, who are shipowners, also focus on and manage very intensively. To solve these problems, this study developed a system that can increase the cleaning effect of the cleaning fluid inside the pipes by increasing the flow of the cleaning fluid inside the pipes in the existing pipe cleaning method.